Police will replace CS tear gas stocks in response to concerns raised over possible health hazards involving the most widely used chemical agent used for crowd dispersal.

Officials at the National Police Agency said Monday that it will dispose of all remaining CS gas, which it has used for more than 30 years, beginning next year.

Instead, police will use pelargonic acid vanillylamide (PAVA), an incapacitant that is believed to be less harmful.

“We plan to destroy all of our CS gas stock, as we’ve acquired PAVA since last year, and there is controversy over the safety of the former. Consequently Korea will be CS gas-free,” an official said.

CS gas causes crying and soreness of the eyes, face and respiratory tract. It has been used as a riot control tool worldwide.

Police are first believed to have used CS tear gas here in 1981. The gas is formed by mixing a solvent ― 2-chlorobenzalmalononitrile ― with water and is shot from water cannons or projectiles. It was effective in dispersing protestors, especially during large-scale pro-democracy demonstrations between the late 1980s and early 1990s.

But police have refrained from using it after an Agency for Defense Development study in 2006 showed that the solvent and a dichloromethane additive could cause cancer.

They disposed of some 49,000 liters of the gas in 2007, but used 2,100 liters in 2009 during protests. They have kept 4,528 liters of the substance for emergency use.

The National Assembly Public Administration and Security Committee had previously recommended police discard the gas.

“We believe CS gas is not that harmful if it is used in regulated doses, but we are replacing it with PAVA to avoid unnecessary disputes in its use,” the official said.

Police have bought 5,880 liters of PAVA, costing 270 million won. They also adopted a natural capsaicin spray in 2008.